It DEPENDS on the slope of V-I graph . as resistivity depends on material the resistance actually MATTERS in case of resistivity.
from graph it's clear that the current in the X WIRE is more than in the current in Y wire (means resistance of X is LESS than Y) (slope of X is more than slope of Y.(Y is having more resistance than X))
so the resistivity of X is less than Y. (Y has GREATER resistivity)